You'd better consult with an expert on this one. All I remember is that the USVI is a special
customs zone. If you travel straight from the USVI to
Puerto Rico or
Florida, you are required to check in at your
destination.
Puerto Rico is not a special
customs zone, so once you clear into the US in Puerto Rico, you don't have to clear again in
Miami, for example.
I don't think you want to
import into the VI, because they have a local excise tax in addition to US customs duties. I don't know what it is for boats, but its 4% for most things.